Multiple space-time scale analysis for interacting branching models

Abstract

We study a class of systems of countably many linearly interacting diffusions whose components take values in [0,∞) and which in particular includes the case of interacting (via migration) systems of Feller’s continuous state branching diffusions. The components are labelled by a hierarchical group. The longterm behaviour of this system is analysed by considering space-time renormalised systems in a combination of slow and fast time scales and in the limit as an interaction parameter goes to infinity. This leads to a new perspective on the large scale behaviour (in space and time) of critical branching systems in both the persistent and non-persistent cases and including that of the associated historical process. Furthermore we obtain an example for a rigorous renormalization analysis. © 1996 Applied Probability Trust.